BOUNCING AVONS ON 99IS

[dcfan2]

ANYONE HAVING ISSUSES WITH AVON VENOM FRONT TIRE BOUNCING.About 35mph front will develope a rythmic bounce.At 40 mph it will go away.running 40-42 psi front. Tire has about 10k on it and about half tread left.Took wheel off and had it checked for balance--ok.Even had them break it down to check inside for problems--none. running new cobra on rear.problem started before rear change.thanks for any input

[Spirited-6]

My 98 Tourer with 880`s on it has done that from day one, 35 MPH bounce. No other problems at any speed.  Would like to hear other veiws.

[pvan]

Could be a few reasons for the guy who has bounced from day one, maybe your front fork springs are weak one side or the other or both? Maybe low on fork oil one side or the other?
For the guy with 10,000 miles most likely air pressure not right at one time or another and the tire wore uneven thus causing the problem.
Net fix for both is check fork springs or better yet replace with new progressives then change fork oil and keep a close eye on tire pressure after you both get new front tires.

[PAVALKER]

Was it balanced or are you using DYNA Beads?   I have heard that balanced tires come out of balance, but DYNA Beads don't.

[R J]

ANYONE HAVING ISSUSES WITH AVON VENOM FRONT TIRE BOUNCING.About 35mph front will develope a rythmic bounce.At 40 mph it will go away.running 40-42 psi front. Tire has about 10k on it and about half tread left.Took wheel off and had it checked for balance--ok.Even had them break it down to check inside for problems--none. running new cobra on rear.problem started before rear change.thanks for any input

What is the date of manufacture on the tire......   Avon had a problem with the front ones a few years back and if you got into some old stock that could be the wobble.  I had 3 do it on me and finally I went with the Metzler tire in front.

[dcfan2]

date code is 4206.tire has about half tread left on it and no flat spots that we could see.hate to get rid of it with so much tread left but cant stand the bounce.balance on tire was dead on.

[BonS]

If you have access to a dial gauge you should measure the tire for being out-of-round.  Raise the front tire off the ground and place a dial gauge on the tread and slowly spin the tire. All manufacturers have a spec for this. You can also run the dial gauge along the rim where the tire bead sits and measure for the same out-of-round condition. Sometimes simply deflating the tire and breaking the bead and then re-inflating the tire can help if the tires bead just didn't set well when the tire was first mounted. Sometimes the high spot on the rim and be placed at the low spot of the tire and things will correct themselves to the manufacturers limits. Of course, a good shop can do this for you cheaply.

[Wags]

I had two Avons go out of round on my 1999 Interstate. Same as you describe. Around 35mph it had a rhythmic bounce. Above 60 mph it wasn't noticeable.

I put the bike up on my stand and fixed a pointer (like a pen or screwdriver) right at the center of the tire, gave it a spin and it was out of round by at least 3/16". Did the same thing on the rear, it too had a problem although not as bad.

Contacted Avon and they were good to me. Tires had maybe 1000 miles on them and they paid for new ones. I think I had to make up the difference for the shop rate. They allow a certain amount and the place I went to for the tire work was charging above their allowance.

[Bonzo]

Cracks developing in the tread grooves

[Ricky-D]

First off, if the axle is good and tight there will be no influence from mismatched shocks. Period!

Some have already hit on the problem. Inconsistency in the tire.

Could be visible like run-out or invisible like tire thread density problems.

Best thing you can do to mitigate the bounce is try different air pressure in the tire.

If you have any indexing in the steering head bearings, the tire problem will amplify the problem.

[pvan]

 Rick D says fork spring problems have no impact on tire wear?  How about when a bike is leaned over while turning the axis of the fork suspension is not perpendicular to the ground and if one or the other of the front forks is bad or irregular pressure the forks will adversely impact the tires contact patch.  How about when the front tire encounters a bump in the road, or what about front forks influence on braking? I think front forks do impact tire wear because the irregular tension causes different pressures on the front tire and the result is extra ordinary tire wear that can sometimes be felt as bouncing or shaking.

[Bob E.]

Rick D says fork spring problems have no impact on tire wear?  How about when a bike is leaned over while turning the axis of the fork suspension is not perpendicular to the ground and if one or the other of the front forks is bad or irregular pressure the forks will adversely impact the tires contact patch.  How about when the front tire encounters a bump in the road, or what about front forks influence on braking? I think front forks do impact tire wear because the irregular tension causes different pressures on the front tire and the result is extra ordinary tire wear that can sometimes be felt as bouncing or shaking.

I'm no fork expert by any means, and what you say makes sense...except that the internals of the Valk forks are completely different from the left leg to the right leg.  Only one leg provides the damping force and the other is just a spring.  So I'm thinking your statements might not be completely accurate.  Not saying you are wrong, I'm just not sure you are right.

[Ricky-D]

Rick D says fork spring problems have no impact on tire wear?  How about when a bike is leaned over while turning the axis of the fork suspension is not perpendicular to the ground and if one or the other of the front forks is bad or irregular pressure the forks will adversely impact the tires contact patch.  How about when the front tire encounters a bump in the road, or what about front forks influence on braking? I think front forks do impact tire wear because the irregular tension causes different pressures on the front tire and the result is extra ordinary tire wear that can sometimes be felt as bouncing or shaking.

You also wrote:

Could be a few reasons for the guy who has bounced from day one, maybe your front fork springs are weak one side or the other or both? Maybe low on fork oil one side or the other?

I was responding to this statement you made.

So you see, I was not making any connection to tire wear.   You made that connection yourself and then you proceeded to beat me with it!   

Get a Life!

[Ricky-D]

Rick D says fork spring problems have no impact on tire wear?  How about when a bike is leaned over while turning the axis of the fork suspension is not perpendicular to the ground and if one or the other of the front forks is bad or irregular pressure the forks will adversely impact the tires contact patch.  How about when the front tire encounters a bump in the road, or what about front forks influence on braking? I think front forks do impact tire wear because the irregular tension causes different pressures on the front tire and the result is extra ordinary tire wear that can sometimes be felt as bouncing or shaking.

I'm no fork expert by any means, and what you say makes sense...except that the internals of the Valk forks are completely different from the left leg to the right leg.  Only one leg provides the damping force and the other is just a spring.  So I'm thinking your statements might not be completely accurate.  Not saying you are wrong, I'm just not sure you are right.

You ought to go ahead and just give in on the front end you know!

Think harder.

The tight axle makes the whole assembly (wheel, lower shock tubes and axle) impersonate  a solid (like steel) u shaped piece of metal that is designed to go up and down inside the other shock tubes that are fastened to the triple trees.  That is the other solid steel acting u shaped piece of the puzzle.

They are designed to slide together as a whole with no flexing.

You should now see that the axle is the weakest part of the assembly and that is why it is imperative to properly torque the axle nut.

That is why I wrote: 

First off, if the axle is good and tight there will be no influence from mismatched shocks. Period!

[Bob E.]

Rick D says fork spring problems have no impact on tire wear?  How about when a bike is leaned over while turning the axis of the fork suspension is not perpendicular to the ground and if one or the other of the front forks is bad or irregular pressure the forks will adversely impact the tires contact patch.  How about when the front tire encounters a bump in the road, or what about front forks influence on braking? I think front forks do impact tire wear because the irregular tension causes different pressures on the front tire and the result is extra ordinary tire wear that can sometimes be felt as bouncing or shaking.

I'm no fork expert by any means, and what you say makes sense...except that the internals of the Valk forks are completely different from the left leg to the right leg.  Only one leg provides the damping force and the other is just a spring.  So I'm thinking your statements might not be completely accurate.  Not saying you are wrong, I'm just not sure you are right.

You ought to go ahead and just give in on the front end you know!

Think harder.

The tight axle makes the whole assembly (wheel, lower shock tubes and axle) impersonate  a solid (like steel) u shaped piece of metal that is designed to go up and down inside the other shock tubes that are fastened to the triple trees.  That is the other solid steel acting u shaped piece of the puzzle.

They are designed to slide together as a whole with no flexing.

You should now see that the axle is the weakest part of the assembly and that is why it is imperative to properly torque the axle nut.

That is why I wrote:  

First off, if the axle is good and tight there will be no influence from mismatched shocks. Period!

Ricky-D...I was actually agreeing with you.   ???  My point to pvan is that the forks are mis-matched by design from the factory so what he was saying and the conclusions he was drawing aren't entirely accurate.   

[pvan]

 Lighten up pal... saying get a life and I am beating you up is way off the mark, You offered your input, I offered mine, and I don' give two $hits if you agree with me that problems related to front suspension will adversely affect front tire wear.